An Algebraic Blueprint for Predicting Turnover Numbers and Endpoints in Photocatalysis.

Photocatalysis is a contemporary research field given that the world's fossil energy resources including coal, mineral oil and natural gas are finite. The vast variety of photocatalytic systems demands for standardized protocols facilitating an objective comparison. While there are commonly accepted performance indicators such as the turnover number (TON) that are usually reported, to date there is no unified concept for the determination of TONs and the endpoint of the reaction during continuous measurements. Herein, we propose an algebraic approach using defined parameters and boundary conditions based on partial-least squares regression for generically calculating and predicting the turnover number and the endpoint of a photocatalytic experiment. Furthermore, the impact of the analysis period was evaluated with respect to the fidelity of the obtained TON, and the influence of the data point density along critical segments of the obtained fitting function is demonstrated.

An Algebraic Blueprint for Predicting Turnover Numbers and Endpoints in Photocatalysis.

The front cover artwork is provided by the Institute of Analytical and Bioanalytical Chemistry and the Institute of Inorganic Chemistry I at Ulm University within the Collaborative Research Center TRR 234 CataLight. The image shows an algebraic approach to generically calculate and predict the turnover number (TON) and the endpoint of photocatalytic hydrogen gas evolution experiments. Read the full text of the Research Article at 10.1002/cphc.202300767.

Thin-Film Waveguide Laser Spectroscopy: A Novel Platform for Bacterial Analysis.

Bacterial sensing based on quantum cascade laser spectroscopy coupled with diamond or gallium arsenide thin-film waveguides is a novel analytical tool for gaining high-resolution infrared spectroscopic information of planktonic and sessile bacteria, as shown in the present study for Escherichia coli. During observation periods of up to 24 h, diamond and gallium arsenide thin-film waveguide laser spectroscopy was compared to information obtained via conventional Fourier transform infrared spectroscopy. The proliferation behavior of E. coli at those surfaces was complementarily investigated using atomic force microscopy and scanning electron microscopy.

Flexible terahertz gas sensing platform based on substrate-integrated hollow waveguides and an opto-electronic light source.

We report on a flexible platform for molecular sensing in the terahertz range. Merging the well-established technologies of near-infrared electro-optic modulation and photomixing realizes a spectrally adaptable terahertz source, which is combined with a new generation of compact gas cells, so-called substrate-integrated hollow waveguides (iHWGs). iHWGs have been developed in the mid-infrared and provide flexibility in the design of the optical absorption path. Here, we demonstrate its suitability for the terahertz domain by presenting its low propagation losses and by measuring rotational transitions of nitrious oxide (N2O). A fast frequency sideband modulation technique results in substantially reduced measurement times and increased accuracy compared to a standard wavelength tuning method.

Graphene-enhanced quantum cascade laser infrared spectroscopy using diamond thin-film waveguides.

Diamond thin-film waveguides were combined with quantum cascade lasers augmented by drop-casted graphene enabling surface-enhanced infrared absorption spectroscopy. Enhancing the signal provides access to an even more pronounced vibrational signature suitable for analytical scenarios where only a small sample volume and/or low analyte concentration levels are prevalent. To demonstrate the utility of this concept, taurine was investigated as a model analyte.

Glucose sandwich assay based on surface-enhanced Raman spectroscopy.

A facile and sensitive glucose sandwich assay using surface-enhanced Raman scattering (SERS) has been developed. Glucose was captured by 3-aminopheyonyl boronic acid (APBA) modified Ag nanoparticles decorated onto a polyamide surface. Then, Ag nanoparticles modified with 3-amino-6-ethynylpicolinonitrile (AEPO) and APBA were used as SERS tags. APBA forms specific cis-diol compounds with glucose molecules avoiding interference by other saccharides and biomolecules in urine enabling its selective detection. As the actual Raman reporter, AEPO exhibited a distinctive SERS peak in the Raman silent region, thus increasing the sensitivity of the glucose detection to 10-11 M. Additionally, the developed SERS assay was reusable, and its applicability in artificial urine samples demonstrated future clinical utility confirming the potential of this innovative technology as a diagnostic tool for glucose sensing.

Atomic force and infrared spectroscopic studies on the role of surface charge for the anti-biofouling properties of polydopamine films.

Antibacterial polymer materials have gained interest due to their capability to inhibit or eradicate biofilms with greater efficiency in comparison with their monomeric counterparts. Among the antimicrobial and anti-biofouling polymers, catecholamine-based polymers - and in particular polydopamine - have been studied due to their favorable adhesion properties, which can be tuned by controlling the pH value. In this study, we used atomic force microscopy (AFM)-based spectroscopy to investigate the relation between the adhesion properties and surface charge density and the pH of electrochemically deposited polydopamine films presenting a dissociation constant of polydopamine of 6.3 ± 0.2 and a point of zero charge of 5.37 ± 0.06. Furthermore, using AFM and attenuated total reflection-Fourier transform infrared spectroscopy (ATR-FTIR), the influence of the surface charge density of polydopamine on bacterial adhesion and biofilm formation was investigated. It was shown that the adhesion of Escherichia coli at positively charged polydopamine is three times higher compared to a negatively charged polymer, and that the formation of biofilms is favored at positively charged polymers.

Icosahedral gold nanoparticles decorated with hexon protein: a surrogate for adenovirus serotype 5.

The development of synthetic particles that emulate real viruses in size, shape, and chemical composition is vital to the development of imprinted polymer-based sorbent materials (molecularly imprinted polymers, MIPs). In this study, we address surrogates for adenovirus type 5 (Adv 5) via the synthesis and subsequent modification of icosahedral gold nanoparticles (iAuNPs) decorated with the most abundant protein of the Adv 5 (i.e., hexon protein) at the surface. CTAB-capped iAuNPs with dimensions in the range of 40-90 nm were synthesized, and then CTAB was replaced by a variety of polyethylene glycols (PEGs) in order to introduce suitable functionalities serving as anchoring points for the attachment of the hexon protein. The latter was achieved by non-covalent linking of the protein to the iAuNP surface using a PEG without reactive termination (i.e., methoxy PEG thiol, mPEG-SH, Mn=800). Alternatively, covalent anchoring points were generated by modifying the iAuNPs with a bifunctional PEG (i.e., thiol PEG amine, SH-PEG-NH2) followed by the addition of glutaraldehyde. X-ray photoelectron spectroscopy (XPS) confirmed the formation of the anchoring points at the iAuNP surface. Next, the amino groups present in the amino acids of the hexon protein interacted with the glutaraldehyde. iAuNPs before and after PEGylation were characterized using dynamic light scattering (DLS), XPS, transmission electron microscopy (TEM), scanning electron microscopy (SEM), and UV-Vis spectroscopy, confirming the CTAB-PEG exchange. Finally, the distinct red shift obtained in the UV-Vis spectra of the pegylated iAuNPs in the presence of the hexon protein, the increase in the hydrodynamic diameter, the change in the zeta potential, and the selective binding of the hexon-modified iAuNPs towards a hexon-imprinted polymer (HIP) confirmed success in both the covalent and non-covalent attachment at the iAuNP surface.

Rational In Silico Design of Molecularly Imprinted Polymers: Current Challenges and Future Potential.

The rational design of molecularly imprinted polymers has evolved along with state-of-the-art experimental imprinting strategies taking advantage of sophisticated computational tools. In silico methods enable the screening and simulation of innovative polymerization components and conditions superseding conventional formulations. The combined use of quantum mechanics, molecular mechanics, and molecular dynamics strategies allows for macromolecular modelling to study the systematic translation from the pre- to the post-polymerization stage. However, predictive design and high-performance computing to advance MIP development are neither fully explored nor practiced comprehensively on a routine basis to date. In this review, we focus on different steps along the molecular imprinting process and discuss appropriate computational methods that may assist in optimizing the associated experimental strategies. We discuss the potential, challenges, and limitations of computational approaches including ML/AI and present perspectives that may guide next-generation rational MIP design for accelerating the discovery of innovative molecularly templated materials.

Rationalizing In Situ Active Repair in Hydrogen Evolution Photocatalysis via Non-Invasive Raman Spectroscopy.

Currently, most photosensitizers and catalysts used in the field of artificial photosynthesis are still based on rare earth metals and should thus be utilized as efficiently and economically as possible. While repair of an inactivated catalyst is a potential mitigation strategy, this remains a challenge. State-of-the-art methods are crucial for characterizing reaction products during photocatalysis and repair, and are currently based on invasive analysis techniques limiting real-time access to the involved mechanisms. Herein, we use an innovative in situ technique for detecting both initially evolved hydrogen and after active repair via advanced non-invasive rotational Raman spectroscopy. This facilitates unprecedently accurate monitoring of gaseous reaction products and insight into the mechanism of active repair during light-driven catalysis enabling the identification of relevant mechanistic details along with innovative repair strategies.

One-Drop Serum Screening Test for Anal Cancer in Men via Infrared Attenuated Total Reflection Spectroscopy.

Rare cancers are a challenge for clinical practice, the treatment experience at major centers to which rare cancers are referred is limited and are the most difficult to diagnose. Research to identify causes or develop prevention and early detection strategies is extremely challenging. Anal cancer is an example of a rare cancer, with the human papillomavirus (HPV) infection being the most important risk factor associated. In the early stages, anal cancer does not exhibit evident symptoms. This disease is diagnosed by means of anoscopy, which diagnoses some cases of early cancer; nevertheless, sensitivity of this test ranges between 47 and 89%. Therefore, the development of new, effective, and evidence-based screening methodologies for the early detection of rare cancers is of great relevance. In this study, the potential of ATR-FTIR spectroscopy has been explored as a sensitive, nondestructive, and inexpensive analytical method for developing disease screening platforms in serum. Spectral differences were found in the regions of 1700-1100 and 1700-1400 cm-1 between the control group and the anal cancer group related to the presence of proteins and nucleic acids. The chemometric analysis presented differences in the spectral fingerprints for both spectral regions with a high sensitivity ranging from 95.2 to 99.9% and a specificity ranging from 99.2 to 100%. This is the first step that we report for a methodology that is fast, nondestructive, and easy to perform, and the high sensitivity and specificity of the method are the basis for extensive research studies to implement these technologies in the clinical field.

Stimulated Raman histology in the neurosurgical workflow of a major European neurosurgical center - part A.

Histopathological diagnosis is the current standard for the classification of brain and spine tumors. Raman spectroscopy has been reported to allow fast and easy intraoperative tissue analysis. Here, we report data on the intraoperative implementation of a stimulated Raman histology (SRH) as an innovative strategy offering intraoperative near real-time histopathological analysis. A total of 429 SRH images from 108 patients were generated and analyzed by using a Raman imaging system (Invenio Imaging Inc.). We aimed at establishing a dedicated workflow for SRH serving as an intraoperative diagnostic, research, and quality control tool in the neurosurgical operating room (OR). First experiences with this novel imaging modality were reported and analyzed suggesting process optimization regarding tissue collection, preparation, and imaging. The Raman imaging system was rapidly integrated into the surgical workflow of a large neurosurgical center. Within a few minutes of connecting the device, the first high-quality images could be acquired in a "plug-and-play" manner. We did not encounter relevant obstacles and the learning curve was steep. However, certain prerequisites regarding quality and acquisition of tissue samples, data processing and interpretation, and high throughput adaptions must be considered. Intraoperative SRH can easily be integrated into the workflow of neurosurgical tumor resection. Considering few process optimizations that can be implemented rapidly, high-quality images can be obtained near real time. Hence, we propose SRH as a complementary tool for the diagnosis of tumor entity, analysis of tumor infiltration zones, online quality and safety control and as a research tool in the neurosurgical OR.

Neuropathological interpretation of stimulated Raman histology images of brain and spine tumors: part B.

Intraoperative histopathological examinations are routinely performed to provide neurosurgeons with information about the entity of tumor tissue. Here, we quantified the neuropathological interpretability of stimulated Raman histology (SRH) acquired using a Raman laser imaging system in a routine clinical setting without any specialized training or prior experience. Stimulated Raman scattering microscopy was performed on 117 samples of pathological tissue from 73 cases of brain and spine tumor surgeries. A board-certified neuropathologist - novice in the interpretation of SRH - assessed image quality by scoring subjective tumor infiltration and stated a diagnosis based on the SRH images. The diagnostic accuracy was determined by comparison to frozen hematoxylin-eosin (H&E)-stained sections and the ground truth defined as the definitive neuropathological diagnosis. The overall SRH imaging quality was rated high with the detection of tumor cells classified as inconclusive in only 4.2% of all images. The accuracy of neuropathological diagnosis based on SRH images was 87.7% and was non-inferior to the current standard of fast frozen H&E-stained sections (87.3 vs. 88.9%, p = 0.783). We found a substantial diagnostic correlation between SRH-based neuropathological diagnosis and H&E-stained frozen sections (κ = 0.8). The interpretability of intraoperative SRH imaging was demonstrated to be equivalent to the current standard method of H&E-stained frozen sections. Further research using this label-free innovative alternative vs. conventional staining is required to determine to which extent SRH-based intraoperative decision-making can be streamlined in order to facilitate the advancement of surgical neurooncology.

Molecularly imprinted polymers for selective extraction/microextraction of cancer biomarkers: A review.

Over recent years, great efforts have been extensively documented in top scientific journals on the development of methods for early diagnosis, treatment, and monitoring of cancers which are prevalent critical diseases with a high mortality rate among men and women. The determination of cancer biomarkers using different optimum methodologies is one of the finest options for achieving these goals with more precision, speed, and at a lower cost than traditional clinical procedures. In this regard, while focusing on specific biomarkers, molecularly imprinted technology has enabled novel diagnostic techniques for a variety of diseases. Due to the well-known advantages of molecularly imprinted polymers (MIPs), this review focuses on the current trends of MIPs-based extraction/microextraction methods, specifically targeting cancer biomarkers from various matrices. These optimized methods have demonstrated high selectivity, accuracy, sorbent reusability, extraction recovery, and low limits of detection and quantification for a variety of cancer biomarkers, which are a powerful tool to provide early diagnosis, prognosis, and treatment monitoring, with potential clinical application expected soon. This review highlights the key progress, specific modifications, and strategies used for MIP synthesis. The future perspectives for cancer biomarkers purification and determination by fabricating MIP-based techniques are also discussed.

Antimicrobial Efficiency of Chitosan and Its Methylated Derivative against Lentilactobacillus parabuchneri Biofilms.

Antimicrobial materials are considered potential alternatives to prevent the development of biofilm-associated contaminations. Concerns regarding synthetic preservatives necessitate the development of innovative and safe natural antimicrobials. In the present study, we discuss the in situ infrared attenuated total reflection spectroscopy (IR-ATR) investigations of the selective antimicrobial efficiency of chitosan in controlling the growth of Lentilactobacillus parabuchneri biofilms. The protonated charges of chitosan were additionally amplified by structural modification via methylation, yielding quaternized derivative TMC (i.e., N, N, N-trimethyl chitosan). To evaluate antimicrobial effectiveness against L. parab. biofilms, IR-ATR spectroscopy provided information on molecular mechanisms and insights into chemical changes during real-time biofilm inhibition studies. The integrated fiberoptic oxygen microsensors enabled monitoring oxygen (O2) concentration gradients within biofilms, thereby confirming the metabolic oxygen depletion dropping from 4.5 to 0.7 mg L-1. IR studies revealed strong electrostatic interactions between chitosan/its water-soluble derivative and bacteria, indicating that a few hours were sufficient to affect biofilm disruption. The significant decrease in the IR bands is related to the characteristic spectral information of amide I, II, III, nucleic acid, and extracellular polymeric matrix (EPS) produced by L. parabuchneri biofilms. Cell clusters of biofilms, microcolonies, and destabilization of the EPS matrix after the addition of biopolymers were visualized using optical microscopy. In addition, scanning electron microscopy (SEM) of biofilms grown on polystyrene and stainless-steel surfaces was used to examine morphological changes, indicating the disintegration of the biofilm matrix into individual cells. Quantification of the total biofilm formation correlated with the CV assay results, indicating cell death and lysis. The electrostatic interactions between chitosan and the bacterial cell wall typically occur between protonated amino groups and negatively charged phospholipids, which promote permeabilization. Biofilm growth inhibition was assessed by a viability assay for a period of 72 h and in the range of low MIC values (varying 0.01-2%). These results support the potential of chitosan and TMC for bacterial growth prevention of the foodborne contaminant L. parabuchneri in the dairy industry and for further implementation in food packaging.

Preprocessing Strategies for Sparse Infrared Spectroscopy: A Case Study on Cartilage Diagnostics.

The aim of the study was to optimize preprocessing of sparse infrared spectral data. The sparse data were obtained by reducing broadband Fourier transform infrared attenuated total reflectance spectra of bovine and human cartilage, as well as of simulated spectral data, comprising several thousand spectral variables into datasets comprising only seven spectral variables. Different preprocessing approaches were compared, including simple baseline correction and normalization procedures, and model-based preprocessing, such as multiplicative signal correction (MSC). The optimal preprocessing was selected based on the quality of classification models established by partial least squares discriminant analysis for discriminating healthy and damaged cartilage samples. The best results for the sparse data were obtained by preprocessing using a baseline offset correction at 1800 cm-1, followed by peak normalization at 850 cm-1 and preprocessing by MSC.

Preclassification of Broadband and Sparse Infrared Data by Multiplicative Signal Correction Approach.

Preclassification of raw infrared spectra has often been neglected in scientific literature. Separating spectra of low spectral quality, due to low signal-to-noise ratio, presence of artifacts, and low analyte presence, is crucial for accurate model development. Furthermore, it is very important for sparse data, where it becomes challenging to visually inspect spectra of different natures. Hence, a preclassification approach to separate infrared spectra for sparse data is needed. In this study, we propose a preclassification approach based on Multiplicative Signal Correction (MSC). The MSC approach was applied on human and the bovine knee cartilage broadband Fourier Transform Infrared (FTIR) spectra and on a sparse data subset comprising of only seven wavelengths. The goal of the preclassification was to separate spectra with analyte-rich signals (i.e., cartilage) from spectra with analyte-poor (and high-matrix) signals (i.e., water). The human datasets 1 and 2 contained 814 and 815 spectra, while the bovine dataset contained 396 spectra. A pure water spectrum was used as a reference spectrum in the MSC approach. A threshold for the root mean square error (RMSE) was used to separate cartilage from water spectra for broadband and the sparse spectral data. Additionally, standard noise-to-ratio and principle component analysis were applied on broadband spectra. The fully automated MSC preclassification approach, using water as reference spectrum, performed as well as the manual visual inspection. Moreover, it enabled not only separation of cartilage from water spectra in broadband spectral datasets, but also in sparse datasets where manual visual inspection cannot be applied.

Spectral Signatures of Oxidation States in a Manganese-Oxo Cubane Water Oxidation Catalyst.

We report IR and UV/Vis spectroscopic signatures that allow discriminating between the oxidation states of the manganese-based water oxidation catalyst [(Mn4 O4 )(V4 O13 )(OAc)3 ]3- . Simulated IR spectra show that V=O stretching vibrations in the 900-1000 cm-1 region shift consistently by about 20 cm-1 per oxidation equivalent. Multiple bands in the 1450-1550 cm-1 region also change systematically upon oxidation/reduction. The computed UV/Vis spectra predict that the spectral range above 350 nm is characteristic of the managanese-oxo cubane oxidation state, whereas transitions at higher energy are due to the vanadate ligand. The presence of absorption signals above 680 nm is indicative of the presence of MnIII atoms. Spectroelectrochemical measurements of the oxidation from [Mn 2 III Mn 2 IV ] to [Mn 4 IV ] showed that the change in oxidation state can indeed be tracked by both IR and UV/Vis spectroscopy.

Autologous platelet-rich fibrin (PRF) augmentation as an add-on therapy in deep surgical site infections (dSSIs) after instrumented spinal surgery: preliminary results of a single institution case series.

BACKGROUND: Deep surgical site infections (dSSIs) after instrumented spinal surgery pose major therapeutic challenges. Standard treatment involves surgical debridement, wound drainage, and long-term antibiotic administration. Autologous platelet-rich fibrin (PRF) constitutes a biomaterial obtained from patients' own blood that contains leukocytes, chemokines and growth factors boosting cicatrization. Due to favorable results reported from other surgical disciplines such as dentistry, orthopedics, maxillofacial and plastic surgery using PRF, the authors hypothesized that PRF augmentation will promote wound healing in dSSIs. OBJECTIVE: To report our preliminary results on the safety and efficacy of autologous-PRF as an add-on therapy on a pilot case series of persistent dSSI after instrumented spinal surgery. METHODS: Among the 293 patients who underwent dorsal decompression and stabilization of the cervical, thoracic, and lumbar spine due to degenerative diseases in our department, 12 patients (4%) presented persisting dSSI after standard wound debridement and antibiotic treatment. PRF augmentation was used during a second surgical revision as an add-on therapy to standard debridement. In all cases, the wound was primarily closed without drains. RESULTS: Wound healing was completed between 14 and 21 days after the second surgical revision in all patients. At a median follow-up of 8 months (range: 6 to 18 months), no recurrence of dSSI nor complications were encountered in any case. CONCLUSIONS: Our preliminary results suggest that PRF augmentation in persistent dSSI after instrumented spinal surgery appears to be a safe and effective strategy to promote wound healing. Prospective controlled studies are required to define the efficiency of PRF more clearly in both treating and preventing dSSI.

[Aerosols and SARS-CoV-2: Statement of the "Expert Group Aerosols" on the development, infectivity, spread and reduction of airborne, virus-containing particles in the air]. / Stellungnahme des "Expertenkreises Aerosole": Aerosole und SARS-CoV-2 ­ Entstehung, Infektiosität, Ausbreitung und Minderung luftgetragener, virenhaltiger Teilchen in der Atemluft.

Aerosols are currently seen as one of the main transmission routes for SARS-CoV-2, but a comprehensive understanding of the processes and appropriate action/adaptation of protection concepts requires the exchange of information across interdisciplinary boundaries. Against this background, the Baden-Württemberg state government launched in October 2020 a multidisciplinary "Expert Group Aerosols" comprising engineers, natural scientists and medical professionals. In its statement, the group has compiled the current state of knowledge in all relevant disciplines in the context of airborne SARS-CoV-2 infection. In addition to the well-known hygiene and social distancing rules, the importance of the correct use of effective masks is emphasized. Furthermore, the necessity for dynamic and correct ventilation is pointed out and illustrated with ventilation intervals and periods for different scenarios as examples. The effectiveness of stationary or mobile cabin air filters as an important component in the protection concept is discussed. The first opinion of the expert group makes it clear that the existing hygiene and social distancing rules offer the best possible protection against SARS-CoV-2 infection only when correctly applied in combination.